If cam surfaces show signs of wear or defects, the cam should be discarded and replaced with a new cam.

If cam surfaces show signs of wear or defects, the cam should be discarded and replaced with a new cam.

• A. Not stated
• B. Only if wear is severe
• C. True
• D. False

Answer: (C)

The main idea is that the cam's surface geometry directly governs how the valves open and close. When cam surfaces wear or show defects, the exact lift and timing can no longer be trusted, which disrupts valve timing, reduces engine performance, and can lead to improper valve clearance or even contact between components. Because the cam and its followers rely on a precise, hardened surface, any wear or crack signs indicate fatigue that could worsen quickly and compromise reliability. Reconditioning a worn cam (regrinding or polishing) can alter the profile, reduce material thickness, and shift timing enough to fall outside specification, so replacing with a new cam restores the intended geometry, hardness, and surface finish. Therefore, the proper maintenance practice is to discard a cam with wear or defects and install a new one. The other options don’t fit because they either imply uncertainty, limit replacement to only severe wear, or suggest that replacement isn’t necessary at all, which would not ensure the required reliability and timing accuracy.

The main idea is that the cam's surface geometry directly governs how the valves open and close. When cam surfaces wear or show defects, the exact lift and timing can no longer be trusted, which disrupts valve timing, reduces engine performance, and can lead to improper valve clearance or even contact between components. Because the cam and its followers rely on a precise, hardened surface, any wear or crack signs indicate fatigue that could worsen quickly and compromise reliability. Reconditioning a worn cam (regrinding or polishing) can alter the profile, reduce material thickness, and shift timing enough to fall outside specification, so replacing with a new cam restores the intended geometry, hardness, and surface finish. Therefore, the proper maintenance practice is to discard a cam with wear or defects and install a new one. The other options don’t fit because they either imply uncertainty, limit replacement to only severe wear, or suggest that replacement isn’t necessary at all, which would not ensure the required reliability and timing accuracy.